Hot lust, perhaps, provided upsetting conclusion (6)
I believe the answer is:
finish
'conclusion' is the definition.
(I know that conclusion can be written as finish)
'hot lust perhaps provided upsetting' is the wordplay.
'hot' becomes 'h' (abbreviation eg on taps).
'lust perhaps' becomes 'sin' (lust is a deadly sin).
'provided' becomes 'if' (eg 'provided it's sunny' means 'if it's sunny').
'upsetting' says the letters should be written in reverse.
'h'+'sin'+'if'='hsinif'
'hsinif' in reverse letter order is 'FINISH'.
(Other definitions for finish that I've seen before include "Complete or terminate" , "Bring to an end" , "Complete (6,3) - See 16" , "Conclude, stop" , "Terminate, conclude" .)